Citizen-Ship DPT

Single to Multi propo
stuart mackay
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Citizen-Ship DPT

Post by stuart mackay » 27 Jun 2020, 17:55

Thought I would share some pics with you of this mid sixties Citizen-Ship DPT 4 channel Digital Proportional that belonged to an old friend of mine, Alan Hawes of AH Designs (famous for their pilot figures)
I dont know too much about it's history, but know that Alan worked for a while in the States and presumably brought this back with him when He returned to Blighty.
There are two airborne packs with a total of ten servos.
Have spent an afternoon cleaning up the set and recharged the Tx Nicad which seems to be showing about 12V!

The Tx looks lovely in its anodised red finish (the Receiver also is anodised) and the sticks are wonderfully engineered open gimbal affairs with mechanical trims on the Allen-Bradley 5k pots.
The throttle stick is interesting as it it has a rack and pinion to create friction (see pic below)
It is a 27Meg set.

The servos are 5 wire plastic cased affairs with linear racks and rotary outputs which you can mix and match. Am unsure if these are Citizen-Ship own brand or from a third party?

If anyone has more technical details and info then please share if you have info as I know precious little about it!
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Tobe
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Joined: 16 Feb 2018, 06:19
Location: Varberg or Stockholm, Sweden

Re: Citizen-Ship DPT

Post by Tobe » 27 Jun 2020, 18:38

Amazing craftsmanship behind this old transmitter from the time when molded plastic parts were considered to expensive or even not possible to manufacture . Today something lika that, all metal, would be tremendously expensive and last but not least think how hard it would be to find the necessary craftsmans. However there was a time when magazines had as project thing line this and modeler in their sheads buit it and flew with it.
I find it already making an aluminum box/case for my transmitter hard enough.
....but one day I might give it a try as I still have plenty of suitable pots left.
The amazing thing is how they succeed to hinge everything in each other. I would imagine that strong centering springs is a necessity

stuart mackay
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Location: Swaffham, Norfolk
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Re: Citizen-Ship DPT

Post by stuart mackay » 27 Jun 2020, 22:33

Tobe wrote:
27 Jun 2020, 18:38
Amazing craftsmanship behind this old transmitter from the time when molded plastic parts were considered to expensive or even not possible to manufacture . Today something lika that, all metal, would be tremendously expensive and last but not least think how hard it would be to find the necessary craftsmans.
The amazing thing is how they succeed to hinge everything in each other. I would imagine that strong centering springs is a necessity
Evening Tobe, have just finished converting to 2.4 using Phil's 4 channel Digispark and one of the new FrSKY XHT modules. All works at first switch on which is really satisfying.

Whilst doing the conversion, I had the stick units out, I took some pics to show the mechanical and production engineering that has gone into their manufacture, are they Flight Link quality, well not far off in my opinion, and they have mechanical trim swinging the pots instead of electrical trims, so quite a complex mechanism!

Now the subjective bit, I havent measured the spring tension but the spring centring doesnt feel overly strong, clearly not as soft as modern sticks, but they have a solid feel to them and the servo resolution seems smooth in operation.
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ozrs
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Joined: 16 Feb 2018, 15:21
Location: West Australia

Re: Citizen-Ship DPT

Post by ozrs » 28 Jun 2020, 04:19

Here is my conversion from a few years back:

Unfortunately, I am missing the original white plastic stick and trim surrounds (not sure if they were provided on all sets?).

viewtopic.php?f=27&t=148
Richard

Tobe
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Joined: 16 Feb 2018, 06:19
Location: Varberg or Stockholm, Sweden

Re: Citizen-Ship DPT

Post by Tobe » 28 Jun 2020, 05:56

Thank you and sure appreciate you took the time, it sure would be a challenging and fun project so it's in my bucket list. Just one question, what's the thickness of the aluminum? 1/32" - 0.8 mm?
I think I can extrapolate the other measurements from the pot as reference.
Cheers & Thanks

Tobe

Pchristy
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Joined: 16 Feb 2018, 13:57
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Re: Citizen-Ship DPT

Post by Pchristy » 28 Jun 2020, 08:39

I remember seeing a CitizenShip analogue system back in the mid 60s, and seeing pictures of their digital sets. I don't ever recall seeing one with those white surrounds for the sticks / trims, though. (Some of those shown in the RC Hall of Fame have them - maybe some of the last made?) http://www.rchalloffame.org/Manufacture ... index.html

12V transmitters were not uncommon back then. My Bonner Digimite uses 12V, and also Allen-Bradley pots - still perfectly smooth nearly 60 years on! Not sure about the servos. Orbit did produce some that had both linear and rotary outputs, but IIRC, they only had one linear output, not two.

12V was necessary at the time, as with the transistors then available, it was difficult to get enough power out to ensure safe operation on 27 MHz. You needed at least 1 watt DC input to the RF output stage to stand any chance of reasonable range, such was the "efficiency" of a telescopic aerial in a hand held box! Many sets of that era were still using germanium transistors, as silicon ones were just too expensive!

Quite a few sets of that era also used machined, open-gimbal sticks. These systems were very expensive at the time, and only made in relatively small quantities. Not many manufacturers could afford the tooling required to produce stick assemblies, so stuck to relatively simple designs. Bonner was one of the few that invested heavily in plastic moulding technology, and in the early days of "digital", many manufacturers used Bonner sticks - even Kraft - and quite a lot used Bonner servos too, though often with their own amplifiers inside.

Personally, I've always had a preference for strong springs and long sticks. I'm not a "thumb on top" flyer! I think it was Phil Kraft who said "Soft springs sell transmitters. Strong springs win competitions!". 'Nuff said! :)

--
Pete

stuart mackay
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Re: Citizen-Ship DPT

Post by stuart mackay » 28 Jun 2020, 18:28

Tobe wrote:
28 Jun 2020, 05:56
Thank you and sure appreciate you took the time, it sure would be a challenging and fun project so it's in my bucket list. Just one question, what's the thickness of the aluminum? 1/32" - 0.8 mm?
I think I can extrapolate the other measurements from the pot as reference.
Cheers & Thanks

Tobe
Here ya go Tobe!
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stuart mackay
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Joined: 01 Mar 2018, 10:38
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Re: Citizen-Ship DPT

Post by stuart mackay » 28 Jun 2020, 18:40

Had a chat with Mike K about drilling holes in a somewhat rare (to the UK at least) Tx case.
But wanted the single channel facility easily accessible as it will probably be used with a period aircraft such as a RudderBug or an early "Multi", so bit the bullet and drilled a 6.2mm hole on the top right and and found a suitable button.
Managed to position the "modern" electronics out of teh way which allowed the re-use of the original PCB to cover everything up.
I still haven't decided what to do regarding the final positioning of teh 2.4 aerial so have temporarily mounted into the existing aerial hole.
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Tobe
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Location: Varberg or Stockholm, Sweden

Re: Citizen-Ship DPT

Post by Tobe » 28 Jun 2020, 18:48

Very well done and congratulations for that lovely piece you have now.
Thanks for de additional info, very helpful so now or whenever it will be I got most relevant info for a possible challenge.

Cheers

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Phil_G
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Re: Citizen-Ship DPT

Post by Phil_G » 28 Jun 2020, 20:17

"Spot the encoder" :D :lol: :D

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